Reverse current relay system



Jan. 2, 1951 L. B. HADDAD 2,536,740

REVERSE CURRENT RELAY SYSTEM Filed Dec. 28, 1946 5 Sheets-Sheet l FIGJ. 84

Inlllllylllll INVENTOR. LABEEB B. HADDAD BY ma, @Maw )LTM ATTO RN EYS.

Jar. 2, 1951 1 B. HADDAD REVERSE CURRENT RELAY SYSTEM Filed Dec. 28, 1946 3 Sheets-Sheet 2 INVENTOR.

' LABEEB B. HADDAD ATTORNEYS.

Jan. 2, 1951 L. B. HADDAD 2,536,740

REVERSE CURRENT RELAY SYSTEM Filed DeC. 28, 1946 3 Sheets-Sheet 3 FIG. 3.

INVENTOR. LABEEB B. HADDAD BY wz, @man ATTORNEYS.

Patented Jan. 2, 1951 REVERSE Vconsum" RELAY sYsfrEM Labeeb E. Haddad, New Haven, Conn., assigner to The YSafety Car Heating and Lighting Company, Inc., a corporation of Delaware Application December 28, 1946, Serial No. 718,989

(Cl. S20-33) Claims.

This invention relates to electrical power systems and, more in particular, toa reverse'current relay of the type used in the electricalsystems :of railway cars.

An `object of this invention is to provide an electrical system of the type .used-on railway cars which is extremely eicient and dependable in operation. A further object is to vprovide-a 'relay switch for use on railway cars which will connect the generator to the battery system at all times when such a connection is desirable. A further object is to provide a relay switch of the above character which is light in weight, sturdy in construction, dependable in operation, and in all ways satisfactory -for use under widely varying conditions. These and other objects will be in part obvious and in part pointed out below.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and in the several steps `and relation and order of each of the same to one or more or the others, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the drawings;

Figure 1 is a partial schematic view of one embodiment of the invention;

Figure 2 is a vertical section of the relay switch of Figure 1;

Figure 3 is a top plan view of vthe switch of Figures 1 and 2; and,

Figure 4 is a sectional View on the line 4-4 of Figure 2.

In the illustrative embodiment of the present invention the electrical system for a railway car is provided with a r-elay switch which'is extremeto Figure 1 of the drawings, the storage battery vsystem for a railway car is represented at 2 and an axle-driven `generator is represented at 4. The electrical load connected across the storage battery is represented at 6 and, for the sake ci simplicity, the switching and voltage control mechanisrns at the load are omitted. AS will be explained Amore fully below, the generator is connected to the battery only when the voltage of the generator is greater than that of the battery; and this connection is provided by a reverse curr-ent relay switch 8. Relay switch f8 is represented somewhat sch'emati'cally vin Figure l but is shown in detail in Figures 2, 3 and Il. Referring to the upper portion of Figure 2, relay switch 8 is 'provided with Aa switch If@ having a Xed contact :i2 and a movable contact it. 'Contact I4 is mounted von a spring arm Iii, the right-hand end of which is nxed to a mounting block I8 by :a pair vof screws I9 (see also Figures 3 and 4).v

The end of arm I5 is electrically insulated from block I3 by flat rectangular insulators 2l above and below the arm and by insulating bushings (not shown) surrounding screws I9. The electrical circuit from contact ill is through arm I6 and thence through a wire attached to the righthand end oi the arm (see Figure l).

Block i8 is rockably mounted on a pair of pivots 2! on the opposite sides of the block and mounted respectively in a pair of brackets (see Figure 4) which are integral and form a U- member, extend freely through the brackets and are threaded into holes in the opposite sides of the block, thus to provide a low-friction mounting for the block. Threaded through block I3 is a horizontal lever rod 25 (see Figure 2) which carries at its left-hand end a connecting rod 24, there being a coupling provided by a pin 26 threaded in lever rod 25 and having its ends projecting through slots 21 in rod 24. The lower end of rod 2d is threaded into the top of an armature 2S which is generally cylindrical but has slightly tapered ends as will be discussed below. Armature 28 is adapted to move up and down a limited distance to open and close switch In; when the armature is in its lower position switch li? is opened, and when in its raised position, switch It is closed. This movement of the armature is facilitated by a counterweight 29 which is threaded onto the right-hand end of lever rod 25; and counterbala-nces the weight of the armature and the movement is vperformed by a magnetic assembly which surrounds the armature.

rlhis magnetic assembly is formed by a magnetic shell 3G and two sets of coils nested therein and forming therewith respectively an upper magnetic circuit and a lower magnetic circuit. Shell 3d has an upper end ring 32; a middle ring 3:3 and a lower end ring 35; and these rings are mounted in xed parallel relationship on a pair of channel members 38 and 4e (see also Figure 3) positioned at opposite sides of the rings. Each ring is held to each of the channel members by three screws l2 and the rings and channel members are of magnetic steel so as to provide, as indicated above, an upper magnetic circuit formed by rings 32 and 3:4 and the upper ends of the channel members, and a lower magnetic circuit formed by rings 34 and 36 and the lower ends of the channel members.

The rings have concentric axial openings in which is fixed a thin walled brass tube 44, the internal diameter of which is such as to permit armature 28 to slide easily up and down within the tube. Mounted on the top of ring 32 is a top bearing disc it which is of brass and which carries a stainless .steel bearing sleeve 68 through which rod 24 extends. Bearing disc 46 is held in place by a plurality of screws 5I) threaded into ring 32. Similarly, at the bottom a bearing disc 52 is clamped to the bottom ring 36 by screws 54, and threaded through the plate is a bearing pin 56. The cylindrical upper end of pin 56 projects into an axial recess 58 in the bottom end of armature 28.

As pointed out above, rod 24 is threaded into the upper end of armature 23 and the armature is moved up and down tc close and openv switch ID. During this movement, the armature is guided by the combined action of tube 44 and bearing pin 55 on the armature and the action of rod 24 sliding in bearing sleeve 48. Brackets 22 are welded to the top of top ring 32, and at the left is a contactor bracket 6B upon which contact I2 is mounted by an arm 62 fixed to the bracket by a pair of screws 64 and insulated therefrom by rectangular flat insulators 65 and insulating bushings (not shown) around the screws.

The coil assembly for the upper magnetic circuit is formed by a voltage coil E8 which is hereafter referred to as the lifting coil and a series or current coil 10 hereafter referred to as the upper series coil. The coil assembly for the lower magnetic circuit is formed by two voltage coils 12 and 'I4 hereafter referred to respectively as the balancing coil and the holdout coil and a lower series coil 16.

Referring again to Figure 1, the coils are connected in the electrical circuit in the manner indicated. The two series coils I0 and 'I6 are connected in series in the main generator current line with one side of coil l0 connected to gen- :erat'or 4 by a line 80 and with the other side of coil 'I5 connected 'through a line E2 to the contact I2 of switch IQ. Contact I4 of the switch is connected through a line 84 to the positive side of the storage battery system. Thus, with 'switch l0 closed and with the generator voltage exceeding that of the storage battery system, a charging current flows through the circuit from the positive side of generator 4 through line SQ, series coils 'ID and 16, line 82, switch I and line 84 to the storage battery system.

Lifting coil 68 and balancing coil I2 also are connected in series, one side of the balancing coil being connected to the negative side of the generator by a line B6 and the other side of the lifting coil 63 being connected through a line 38 to contact l2 of switch Ill. Contact I2 also is connected to the positive side of the generator through the low resistance circuit formed by line 82, series coils 'i6 and 10, and line 8B. Therefore, lifting coil 63 and balancing coil 'I2 carry a cur rent which varies directly with the voltage of the generator, and, as will be discussed below, this current flows through series coils 'I0 and lt.

Holdout coil 'I4 is connected at one side by a line 99 to the positive side of the generator and at the other side through a line 92 to the positive side of the battery. As pointed out above, the positive side of the battery system is connected to contact I4 of switch lll and the positive side of the generator is connected through the low-resistance series coils 'i and 7S to contact I2 of the switch. Therefore, the holdout coil is connected directly across switch il! so that when the switch is closed, this coil exerts -no effect, whereas when the switch is open it carries a current which varies in direction and. magnitude with the relative values of the voltages of the generator and the storage battery System. Thus, when the voltage of the storage battery system exceeds that of the generator, switch I is normally open and a battery-discharging current flows through the holdout coil 34 and the generator, and, when the generator voltage exceeds that of the storage battery system, the direction of this current is reversed. At all times the magnitude of the current varies directly with the difference between these two potentials, so that when the voltage of the generator equals that of the storage battery system, there is no current flow through the holdout coil. When switch I9 is closed, there is no appreciable iiow of current through the holdoutvcoil because the resistance of series coils 'IIJ and 16 is small, and therefore the voltage drop across these coils is small even when there is a heavy current flow therethrough.

The lifting coil 68 has approximately 1% more turns in it than does the balancing coil 12, and these two coils are arranged to exert opposing effects; that is, the lifting coil tends to move the armature up so as to close switch I0, whereas the balancing coil tends to move the armature down so as to open the switch. The same current ows through both coils so that the slightly larger number of turns in the lifting coil causes it to exert a corresponding greater force for any given current value. As indicated above, the upper series coil I is positioned in the magnetic circuit of the lifting coil, and the lower series coil 'it and holdout coil 'I4 are positioned in the magnetic circuit of the balancing coil l2.

The coils are so wound and connected that, when the generator voltage exceeds the battery voltage, the lifting coil K68 is assisted by its associated series coil 1D, Whereas the balancing coil is opposed or bucked by its associated series coil 76. However, when the voltage of the battery exceeds that of the generator, the effect of each of the series coils is reversed so that the lifting coil is opposed or bucked by its series coil, and the balancing coil is assisted by its series coil. Furthermore, when the voltage of the battery exceeds that of the generator, the holdout coil I4 assists the balancing coil, but when the generator voltage is above that of the battery, the holdout coil bucks the balancing coil.

As pointed out above, the lifting coil 6'8 and the balancing coil I2 are connected in series across the generator 4, and one side of this series circuit is connected to the juncture of the battery and the generator, whereas the other side of this series circuit is connected on the generator side of switch I0. Furthermore, the series coils 'IU and 16 are connected in series between the generator and the switch, and therefore, current which ows from the generator through the lifting and balancing coils also ows through the two series coils.

With this arrangement, when the switch is open, a rise in the generator voltage causes current to flow in the lifting coil and the balancing coil, and this same current owing through the two series coils produces additional effects which tend to close the switch; that is, the lifting coil is assisted by its series coil whereas the balancing coil is bucked by its series coil. As pointed out above, the lifting coil has 1% more turns than the balancing coil, and therefore the net eifect resulting from the two coils working in opposition is a force tending to close the switch. This switch-closing force is small and is of the magnitude of 1% of the gross force of the lifting coil which isithe force which would' be exerted bythe lifting coil if it were not opposed by the-balancing coil. However, the series coil associated with the lifting coil adds an additional force of approximately 1/2% of the total force of the lifting coil and the balancing coil is. ,weakcned byY its series coil to a similar extent. Thus, the-two series coils produce an additional net force which is 1% of the force which would be exerted by the lifting coil if it were not opposed by the balancing coil. This effect of the series coils isadded to this effect of the lifting coil to give a total switch-closing force equal to 2% of the gross force of the lifting coil.

As pointed out above, the holdoutcoil augments the effect of' the balancing coil 12. as long as the voltage of the battery exceeds that of the generator, and, therefore, when the generator is stationary or operating at low speed, the holdout coil produces asubstantial effect tending to hold the switch open. However, as the speed of the generator increases so that its voltage rises to that of the battery, the current ilowing through theholdout coil diminishes towards zero. At any time that the voltage of the generator exceeds that of the battery, the direction off the current flow in the holdout coil is reversed so that this coil then bucks the balancing coil.

As indicated above, counterweight 29 is threaded onto lever rod 25 and therefore the counterbalancing effect of the counterweight is adjusted by turning it on the rod thereby moving yit longitudinally of the rod, During use the counterweight is so adjusted and the other components of the assemblyV are ofsuch magnitude that the switch closes substantially at the time the voltage of the generator exceeds that of the battery system.

When the switch is open and the voltage of the battery system exceeds that of the generator there is` av substantial flow of current through holdout coil 14, the effect of which is additive to the `effect of balancing coil '12. When the voltage of the generator is low and switch lil is oben there is no appreciable current flow through lifting coil 68 and balancing coil '12, and the effect of the holdout coil is very substantial and is suicient to insure that the armature will not rise to. close the. switch.

The factors which are most important at the time of the closing of switch I!) have been referred to above but now will be reviewed briefly. Lifting coil 5B has approximately 1% more turns than does balancing coil 'l2 and therefore the current flowing from the generator through these two coils exerts a net armature-lifting or switchclosing effect and this same current owing is closed, there is no appreciable charging current flowing immediately after the closing of the switch and therefore the effects fof the seriesV coils 10 and 16 are not changed materially; and there is no substantial change in the generator voltage and 'therefore theeffects oi the lifting and balancing coils are not changed materially. Thus,v duri-ng normal operation the speed of the generatol` is. increased gradually so that the generator voltage rises to and` then slightly exceeds that of the battery system at. which time switch it. closes.

After switch l is closed a further increase in the generator voltage causes a battery-.charging current t0 iiow from the generator through the battery system. rihe switch is held closed until such time as the voltage of the batter-y system beech greater than that of the generator, which condition may result from a rise in the battery voltage or a reduction in the generator voltage, and in such event switch IS will be opened promptly. The switch is opened by the higher voltage of the battery System causing a.

reverse current flow through series coils "IllN and i3; the effect of this reverse current in coil 10 to weaken the effect of lifting coil 5 8 and the eifect of this reverse current in coil T6k is to strengthen balancing coil l2. Therefore, armature 2S is pulled down because the strength, of the lower or switch-opening magnetic circuit ex, seedsV that of the upper or switch-closing magnetic circuit. At the time switch i9 is opened the holdout coil 14, becomes energized and its effect is to aid coil l2; therefore the switch is held open.

During operation, a very high degree of sensitivity is obtained by carefully controlling the balance between the two magnetic circuits. In this regard the degree of saturation of the mag;- netic paths at the critical instanceA of closing or opening the switch is quite important. Also of impo-.ence is the air in each magnetic `circuit between the respective end of the armature and the adjacent end ring. In this embodiment the ends of armature 28 are tapered at an angle of 5 degrees so as to provide surfaces which are substantially truste-conical. The accurate alignof armature 2S maintains an even balance and a proper distribution of the magnetic flux during operation.

As many possible embodiments may be made of the above invention. and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. In an electrical system of the character described wherein a generator of variable voltage is adapted to be connected to charge a battery when the generator voltage is higher than the battery voltage, a switch-operating mechanism comprising, a pair of potential coils comprising a rst potential coil which tends to close the switch and a second potential coil which tends to open the switch, said coils being connected at one side adjacent the switch and on the generator side of the switch and being connected their other side to the other side of the generator, a pair of current coils connected in series and between the generator and the switch, and a third potential coil connected in parallel with the switch and adapted to carry a control current the value and sense of which depend upon the relative values of the generator' voltage and the battery voltage, said current coils being positioned re.- spectively adjacent said first and second poten.- tial coils and being adapted to augment the efe fect of said irst potential coil and to decrease thefefect of said second potential coil when' cur,y

rent is owing from the generator through the battery and being adapted to produce the opposite effects when current is flowing from the lbattery through the generator.

2. In an electrical system of the character described wherein a generator of variable voltage is ladapted to be connected to charge a battery when the generator voltage is higher than the battery rvoltage, a switch-operating mechanism comprising, a pair of potential coils comprising a first ypotential coil which tends to close the switch and a second potential coil which tends to open the switch, said coils being connected at one side adjacent the switch and on the generator side of the switch and being connected at their other side to the other side of the generator, a pair of current coils connected in series and between the generator and the switch, and a third potential coil connected in parallel with the switch and adapted to carry a control current the value and sense of which depends upon the relative values of the generator voltage and the battery Voltage, said lcurrent coils being positioned respectively adjacent said rst andsecond potential coils and being adapted to augment the effect of said rst potential coil and to decrease the effector said second potential coil when current is flowing from the generator through the battery and being adapted to produce the opposite effects when current is flowing from the battery through the generator, said first and second potential coils being connected in series and said first coil having substially one per cent more turns than said second potential coil.

3. In an electrical system for controlling the connection between a generator and a storage ibattery in which the generator is connected across the storage battery with a switch in the circuit therebetween, the combination of a first potential coil, a second smaller potential coil, said potential coils being connected in series between one side of said generator and one side of said switch, said first potential coil being associated with said switch and constructed to exert a clos- -ing force on said switch, said second potential coilV being associated with said switch and constructed to exert an open force on said switch, a current coil associated with said first potential coil and in the magnetic circuit thereof, a current coil associated with said second potential coil and in the magnetic circuit thereof, said current coils being substantially identical and connected in series between one side of the gen- .erator and one side of the switch, `said potential coils bridgingsaid generator, and a hold-out coil connected between said generator and said storage battery and bridging said switch, said holdout coil being associated with said second potential coil and in the'magnetic circuit thereof, said 1hold-out being constructed to oppose said second potential coil when the generator voltage is above the battery Voltage and vice versa.

. 4. In an electrical system for controlling the connection between a generator and a storage batteryv in which the generator is connected across the storage battery with a switch in the circuit therebetween, thecombination of a'rst potential coil, a second smaller potential coil Vadapted to exert substantially one per cent less magnetic force than said first potential coil, said potential coils being connected in series between one side of said generator and one side of said switch, said first potential coil being associated :with said switch and constructed to exert a clos- -ng force on saidA switch, said 'secondpotential coil being associated with said switch and constructed to exert an opening force on said switch, a current coil associated with said rst potential coil and in the magnetic circuit thereof, a current coil associated with said second potential coil and in the magnetic circuit thereof, said current coils being substantially identical and connected in series between one side of the generator and one side of the switch, said potential coils bridging said generator, and a hold-out coil connected between said generator and said storage battery and bridging said switch, said holdout coil being associated with said second potential coil and in the magnetic circuit thereof, said hold-out coil being constructed to oppose said second potential coil when the generator voltage is above the battery voltage and vice versa.

5. In an electrical system for controlling the connection between a generator and a storage battery in which the generator is connected across the storage battery with a switch in the circuit therebetween, the combination of an armature connected to said switch to open and close it, a first potential coil, a second smaller potential coil, said potential coils being connected in series between one side of said generator and one side of said switch, said first potential coil being associated with said armature and constructed when energized to move said armature in a direction to close said switch, said second potential coil being associated with said armature and constructed when energized to move said armature in a direction to open said switch, a current coil associated with said rst potential coil and in the magnetic circuit thereof, a current coil associated with said second potential coil and in the magnetic circuit thereof, said current coils being substantially identical and connected in series ybetween one side of the generator and one side of the switch, said potential coils LABEEB B. HADDAD.

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